Oihana PHP

startOfWeek.php

Table of Contents

Functions

startOfWeek()  : DateTimeImmutable
Returns the first representable instant of the week containing a date.

Functions

startOfWeek()

Returns the first representable instant of the week containing a date.

startOfWeek(DateTimeInterface $date[, int $firstDayOfWeek = 1 ]) : DateTimeImmutable

A new DateTimeImmutable is returned, set to 00:00:00.000000 on the first day of the week ; the source date is never modified. The timezone of the returned value is the one carried by $date.

$firstDayOfWeek uses the ISO-8601 numbering also returned by DateTime::format( 'N' ) : 1 for Monday through 7 for Sunday. It defaults to 1 (ISO-8601 / most of the world) ; pass 7 for the US/Canada convention (week starts on Sunday).

Parameters
$date : DateTimeInterface

The source date.

$firstDayOfWeek : int = 1

The first day of the week, 1 (Monday) to 7 (Sunday). Default 1.

Tags
throws
InvalidArgumentException

If $firstDayOfWeek is outside [1, 7].

DateMalformedStringException

Never thrown in practice (the modifier is always well-formed).

example 
use function oihana\core\date\startOfWeek;

// 2026-03-18 is a Wednesday.
startOfWeek( new DateTimeImmutable( '2026-03-18 14:30:45' ) )    ; // 2026-03-16 00:00:00.000000 (Monday)
startOfWeek( new DateTimeImmutable( '2026-03-18 14:30:45' ) , 7 ); // 2026-03-15 00:00:00.000000 (Sunday)
author

Marc Alcaraz (ekameleon)

since
1.2.0
Return values
DateTimeImmutable —

A new immutable date, at the start of the week containing $date.

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